The present disclosure relates to medication delivery and more particularly to delivery of a pain controlled analgesic (“PCA”).
Infusion pumps are used to administer liquid drugs to patients. The liquid drug is supplied from a source of the drug and delivered to the patient via a catheter or other injection device. The infusion pump controls the manner in which the liquid drug is infused to the patient. The pump can have various modes of infusion. An infusion pump can operate in different modes of infusion, such as: (i) a continuous mode in which the pump delivers a single volume at a single rate; (ii) an auto-ramp mode in which the pump delivers the liquid drug at a rate that gradually increases to a threshold rate, remains at the threshold rate for a period of time, and then gradually decreases; (iii) an intermittent mode in which the pump delivers discrete liquid volumes spaced over relatively long periods of time, such as a liquid volume every three hours; (iv) a custom mode in which the pump can be programmed to deliver a unique infusion rate at discrete time periods; and (v) a pain controlled analgesic (“PCA”) mode during which the pump periodically infuses boluses of an analgesic in response to requests by the patient.
The PCA delivery has a number of benefits including: (i) a time savings between when the patient feels pain and/or the need to receive analgesia and when the drug is administered; (ii) a reduction of workload of the nursing staff (an amount of the prescribed analgesic, enough for multiple doses, is pre-loaded into the infusion device and delivered via PCA mode); (iii) reduction of the chance for medication error (PCA programmed per physician's order for amount); (iv) patients receive medicine when they need it, instead of having to wait for the nursing staff; (v) patients who use PCA devices have reported better analgesia and lower pain scores than those patients who have to request analgesia from the nursing staff; and (vi) PCA provides a measurement of how much pain an individual patient is experiencing from one day to the next.
PCA modes of drug delivery involve the intravenous, epidural, or subcutaneous administration of a liquid opioid. The infusion pumps currently in use for PCA in some instances give the clinician two parameters to set when prescribing a given drug for a patient: (i) a dose or bolus amount of drug administered whenever the patient presses a button and (ii) a lockout interval which determines how soon after a bolus is administered that a second bolus can be delivered if the patient presses the button again. If a patient presses the button before the lockout interval has elapsed, the PCA pump ignores the request. The dose and lockout are programmed into the pump for an individual patient and drug combination. The dose is prescribed based on the clinician's assessment of the patient's drug or opioid requirement (depending on weight and habituation. The lockout interval is generally set depending on the time to onset of clinical effect of a given drug. The lockout interval is used to prevent a patient drug overdose resulting from giving himself or herself another bolus before the previous bolus has had a chance to take effect.
Sometimes a third parameter is programmed into a pump providing PCA. This is the flow rate of a continuous infusion of medication providing a background of opioid on top of which PCA is added. The continuous infusion is adjusted to provide the minimum amount of drug needed by a patient over time. The PCA component then allows the patient to administer extra (rescue or break-through-pain) doses as needed. This technique of using a continuous infusion along with PCA minimizes the requirement for a patient to push the button repeatedly as a bolus wears off. This is particularly useful at night when the patient's sleep would otherwise be interrupted regularly.
The PCA button is connected to the infusion pump via a cord. The infusion pump supplies an analog voltage to the button. The infusion pump's electronics recognizes a patient's closure of the PCA button by detecting a change in voltage level, which is normally not seen but seen when the button is pressed.
The analog cables can be prone to a number of errors. A frayed wire or wires within the cord may not allow current to flow or enough current to flow to trigger the electronics when the patient pushes the PCA button, rendering the pump unable to deliver a bolus of analgesic, or possibly delivering a bolus when it is not needed or has not been requested. Or, the wires can become short circuited, damaging electrical components in the pump or opening a fuse, which may need to be replaced, and may also lead to improper analgesic dosage delivery.
A need accordingly exists for an improved PCA input apparatus and method.